The present invention relates to a medication delivery apparatus, and in particular, to an antistatic medication delivery apparatus.
Medication delivery systems are used, in general, to administer medication to a user. For example, aerosol delivery systems are configured to deliver a medication in aerosol form to the lungs of the user. Other systems deliver the medication to the nasal passageways of the user. Some systems use a pressurized metered-dose inhaler (pMDI), which typically includes a container in which medication particles are stored under pressure, and an actuator used to dispense the medication from the container.
In other systems, a holding chamber or spacer is connected to one of the container or actuator, as shown for example in U.S. Pat. No. 6,293,279, which is hereby incorporated herein by reference. The holding chamber reduces the need for the user to coordinate activation of the pMDI canister with inhalation, helps reduce the delivery of nonrespirable medication particles from the canister, and helps reduce the impaction of medication particles in the user's oropharnyx and upper airway. In some configurations, shown for example in the U.S. Pat. No. 6,293,279 and U.S. Pat. No. 5,881,718, the apparatus can be provided with one or both of an inhalation and exhalation valve(s) at an output end of the chamber. The output end is typically configured with a mouthpiece, which is received in the mouth of the user, or with a mask, which is placed over the mouth and nose of the user.
Often, holding chamber devices are made of various plastics, such as polypropylene or polycarbonates. However, plastic materials typically have relative high surface resistivities, typically greater than 10E12 ohm/sq. As such, the interior of the chamber can become electrostatically charged, thereby causing some of the medication particles in the aerosol to deposit on the walls and/or other parts attached to or forming part of the holding chamber. As disclosed in U.S. Pat. No. 6,435,176, for example, one solution to this problem is to provide a spacer made of metal or other materials having resistivities below 10E9 ohm. However, metal spacers or holding chambers, made for example of stainless steel or aluminum, are relatively expensive to manufacture and are heavy and more difficult to handle. In addition, metal spacers or holding chambers do not allow the user or caregiver to visualize the delivery of medication from the chamber. Likewise, many plastics, if formed with antistatic additives, such as metal fibers, are not see-through and can obstruct a view of the interior of the chamber. In addition, plastic components having an antistatic surface coating can tend to degrade and lose their antistatic properties over time, e.g., within about a year.
Another solution is to periodically wash a plastic holding chamber with a detergent. However, such a solution can be cumbersome. Accordingly, the need remains for an improved holding chamber made of plastic, preferably clear, having inherent substantially permanent antistatic properties.